Metallic alloy and method of making same



and useful Improvements in stair THERON D. STAY, OF CLEVELAND, OHIO,ASSIGNOR TO THE ALUMINUM CASTINGS COMPANY, OF CLEVELAND, OHIO, ACORPORATION OF OHIO.

METALLIC ALLOY AND METHOD OF MAKING SAME.

No Drawing. v i

To all whom it may concern:

Be it known that I, THERON D. STAY, a citizen of the United States,residing at Cleveland, in the county ofCuyahoga and State of Ohio, haveinvented certain new Metallic Alloys and Methods of Making Same, ofwhich the following is a specification This invention relates moreespecially to an aluminum alloy and the method of making it.

One object of the invention is to produce an aluminum alloy having thelow specific gravity characteristic of aluminum and at the same timepossessing certain characteristics, not possessed by-that metal, whichespecially adapt the alloy for the production of castings andparticularly castings in which the constituent material is irregularlydistributedvas to bulk and which must lend themselves to machiningbearing qualities.

To these ends I have produced an aluminum alloy containing aluminum,copper and titanium. These'metals have melting points that differ widelyfrom each other; and this fact, and other factors as well, give rise tocertain difliculties in the'production of the alloy.

Therefore, a tion has been to further object of my invendevelop' aprocess by which the improved alloy can be produced econo'mically withrespect to time and the labor and apparatus employed, and which at thesame time permits of close technical control.

At the outset it may be briefly explained that the process erablydividedinto four distinct stages, as

follows: (I) The production of a copper alloy cont'aming'copper,aluminum and titanium, with the copper largely predominant; (2)- theproduction of an aluminum alloy containing aluminum, copper andtitanium, in which the major constituents are aluminum and copper, withthe amount of aluminum somewhat greater than that of copper; theproduction of an aluminumcopper alloy in which the two'metals arepresent in substantially equal amounts; and (4) the production of thefinal alloy containing aluminum, copper and titanium in the desiredproportions.

The alloy produced in the first stage of i the process preferably has acomposition, by

and have good Specification of Letters Patent. Patented SEEN]. 7, 192(1Applicationifiled March 6, 1917. Serial No. 152,791.

6% titanium. To produce this alloy there of making the alloy is prefvu'id, any excess over may be placed in an electric furnace titanium oxidand enough alumlnum to, reduce the titanium plus ten or twelve per cent.

excess, together with the proper amount of I copper, and allowance forvolatilization of the copper, due to the high temperature, being made.The alloy which is thus produced in an electric furnace is very toughand should be cast into relatively thin plates so that it can be cutinto pieces suitable for charging in crucibles. In passing, it isobserved that this alloy has a melting point very materially lower thanthe melting point of titanium, thus affording the latter metal in a formin which it can be handled at lower temperatures.

In the second stage of the process I produce an alloy which preferablyhas a composition substantially as follows: 52.1% aluminum; 46.5%copper; and 1.4% titanium. In producing this latter alloy I take 100lbs. of pure lake copper or electrolytic copper and 100 lbs. of thecopper-aluminumtitanium alloy produced in the electric furnace and meltthem down preferably in an oil-fired furnace of the tilting type, usingcrucible with constant stirring; and at this.

stage the molten alloy turns from a red color to white and becomes moreliquid. It seems that the "addition of the solid aluminumcopper alloy tothe mixture prodiices an alloy having a lower melting point; and atthere appears to be a rise in temperature, indicating that an exothermicthe same time reaction-is taking place.

If the aluminum-copper chill is added at the proper time the entire50'lbs. may be used. However, if the metal in the crugible is allowed tobecome too cold, only enough of the should be added to make itthoroughly liqthis amount causing the aluminum-copper alloy.

whole mixture to become pasty so it could not be readily separated fromthe slag and dross.

The molten'alloy in the crucible is next fiuxed with zinc chlorid whichcauses the dross and slag to be easily separated from the molten metal.After the slag has been carefully skimmed off with an iron skimmer themolten metal is poured slowly into a bath of 150 lbs. of moltenalummum-copper alloy containing threeper cent. copper, this latter alloyhaving been heated in a suitable holding or mixing furnace.- Thisfurnace is preferably placed so that the metal in the crucible can bepoured directly into it so thatdissipation of heat from the molten massis reduced to a minimum, it being necessary to avoid any freezing of themetal in the crucible before it is alloyed-with the material in themixing furnace. The bath must be constantly stirred while the cruciblemetal is being poured to keep the heavier elements from settling to thebottom of the pot before theyhave opportunity to ziial'loy with thelighter aluminum. At this point any of the -aluminum-copper chill whichwas not used in the crucible may be added to the bath. After fluxingwith zinc chlorid and skimming off the dross the alloy may be pouredinto ingot molds.

I I prefer to addthe aluminum-copper al- .loy in solid form, asdescribed above, be-

cause the solid-metal gives the molten bath.

In the third stage, above referred to, of the process I produce analuminum-copper .alloy containing equal parts, by wei ht, of

the two metals. For this purpose melt 200 lbs. of lake copper orelectrolytic copper in a tilting furnace under a cliarcoal cover, in amanner familiar to all acquainted with the art. In the meantime I melt100 lbs. of a three. per cent. copper alloy of aluminum and introduceinto it lO6'lbs; of ingot aluminum. Into this latter metal I then pourthe moltencopper, stirring, with an iron skimmer, to insure a uniformmixture. The aluminum is added in' ingot form, as above stated, to coolthe alloyand prevent it from attacking the iron pot. .After fluxing withzinc chlorid the metal may be poured into ingot molds.

I come now to the fourth stage of my complete the charge.

poses.

However, the important process in which I produce the final alloy,.;

which preferably has a composition, by weight, as follows:

Aluminum 88.00% to 90. 00% Copper 12. 00% to 10. 00% Titanium 0.10% orunder.

In producing this final alloy I take eight pounds of thealuminumcopper-titanium alloy producedin the second stage, abovereferred to, of the process; sixteen pounds of the,aluminum-copper alloyproduced in the third stage; and seventy-six pounds of pure aluminum;and these metals I place in a molten bath of 100 pounds of scrap alloy.of the same composition as that which is to be produced. Enough of thescrap is added to Then when this has been melted down, and reaches atemperature not to exceed1550 F., and the mass thoroughly stirred it isready for casting pur- On a consideration of the several stages in whichthe process is preferably carried out,

as above set forth, it will be observed that the amount of metal handledin the electric furnace at its high temperatures; may be, and inpractice is,

to minimize the amount of metal heated to the comparatively hightemperature necessary to melt the copper, and to correspondingly reducethe amount of time consumed and the capacity of the cruciblemeltingfurnaces which, as will readily be understood, are much more expensivethan the iron furnaces which can be used with the lower workingtemperatures of the fourth stage where the bulk of metal employed ismuch larger. In addition, by dividing the process into the stages as setforth, the constituent materials for the final stage are produced inthe-form of pigs which can be analyzed, Weighed and proportioned con"-veniently and in a manner to effectively contro the composition of. thefinal product.

I prefer, in casting my improved alloy, to pour it at a temperature ofabout 1350 F. When the metal is poured at the right temperature thecasting has a speckled or mottled appearance, while if it is poured toohot, this. speckled appearance gives'way to a solid white aspect and thecasting is usually-found to be porous.

When the process, above described. is carefully followed an alloy issecured which has remarkable characteristics. In particular it has a lowcrystallization shrinkage, and this makes it especially useful inproducing castings in which the material is unevenly distributed, withrelatively thin parts adjacent thick parts, and in castings of intricateshapes. can be made of thisalloy' having a fine- Furthermore, castingsrelatively small. Furthermore, by following the procedure in thesecondand third stages, I am enabled grained structure and-a degree ofhardness that produce excellent machining qualities; and these castings,when machined, have remarkably good bearing qualities.

I have found that the alloy is especially adapted for the production ofpiston castings. Such castings, when machined,-arc capable of taking ahigh polish, are sufficiently hard to withstand abnormal wear when incontact with other metallic surfaces, such .as the cast iron cylinderwalls of internal combustion engines, and will not score the ironsurfaces like other aluminum alloys with which I am familiar.Furthermore, my improved alloy will not soften at temperaturesencountered in internal combustion engine cylinders. Again this alloycan by heat treatment be given a permanentexpansion to, obviatedifiiculties incident to the so-called growth which is characteristic ofmost aluminum alloys.

In describing the composition of my improved alloy and the method ofproducing it, 1 have indicated approximately the relative amounts of thevarious materials which I prefer to employ. It is to be understood,however, that the relative amounts of the constituent materials may bevaried to some extent without seriously affecting the quality of theproduct. Again, in the first stage of the process, the excess aluminummay be cut down as much as desired, providing, of course, acorrespondingly larger amount is added in one of the later stages of theprocess. And, again, where I have specified the use, as constituentmaterial, of an aluminum alloy containing 3% copper, I believe that purealuminum might be used, or an alloy containing more or less than 3% ofcopper. Of course it will be understood that the apparatus employed incarrying out the process may be varied widely to suit conditions inparticular cases without materially affecting the product secured.

/Vliat I claim is: V,

1. An aluminum alloy composedof aluminum in a predominating amount,copper in appreciable amounts and titanium.

2. An aluminum alloy composed of aluminum in a predominating amount,copper in appreciable amounts and titanium up to 10%.

An aluminum alloy containing aluminum, copper and titanium inapproximately the following proportion by weight: alumi- Hum 88% to 90%,copper 12% to 10%, and titanium 0.10% approximately.

"4:. An alloy of aluminum, copper ant titanium, in which the aluminumlargely predominates, which is characterized by low crystallizationshrinkage, and, in the solid state, by relatively great hardness and afine-grained structure having good bearing qualities.

5 The method of forming an alloy containing a metal of relatively highmelting point and a metal of relatively low melting point which consistsin first forming an alloy whose constituents include the said highmelting point metal and a metal having a melting point between those ofthe other two metals, and then combining with the last named alloy saidlow melting point metal.

6. The method of forming an alloy containing a metal of relatively highmelting point and a metal of relatively low melting.

point which consists in first forming an alloy whose constituentsinclude the said high melting point metal and a metal having a meltingpoint between those of the other two metals, combining with the lastnamed al loy a mixture of the medium and low melting point metals, andthereafter combining with the resultant alloy additional amounts ingsaid alloy with copper and aluminum in proportions to increase thepercentage of aluminum.

8. The method of producing an alloy of aluminum, copper and titaniumwhich consists in forming an alloy of copper, aluminum and titanium inwhich the copper largely predominates, combining said alloy with copperand aluminum in proportions to increase the percentage of aluminum,

and melting the alloy resulting from the last step with copper andaluminum in proportions to still further increase the percentage ofaluminum, thereby producing an alloy of aluminum, copper and titanium inwhich the aluminum largely predominates.

9. The method of forming an alloy of aluminum, copper and titanium inwhich the aluminum largely predominates, which consists in meltingtogether copper and an alloycontaining copper, aluminum and titanium inwhich the copper largely predominates, adding to the molten productmetal in the solid state consisting predomi-' nantly of aluminum, andthereafter comof copper and aluminum in proportions to 'bining with thealloy thus obtained amounts increase the percentage of aluminum in thealloy. I 10. The method of forming an alloy of aluminum, copper andtitanium in which the aluminum largely predominates, which consists inmelting together copper and analloy containing copper, aluminum andtitanium in which the copper largely predominates, adding to the moltenproduct metalin the solid state consisting predominantly of aluminum,combining the resultpredominantly of aluminum to a moltenant productwith a molten alloyof aluminum and copper in which the aluminumpredominates, and combining with the last resulting alloy aluminum andcopper in proportion to increase the percentage ofaluminum in the alloy.

11. The steps in the production of an alloy of aluminum, copper'andtitanium in which the aluminum largely predominates, which consist inadding a metal consisting mixture of copper, aluminum and titanium in'which the copper predominates, and then pouring the resultant productinto a bath of molten metal consisting predominantly of aluminum.

- melting point and a metal of relatively low melting point in which thelatter largely predominates, which consist in adding a 9 metalconsisting predominantly of the low melting point metal to a moltenmixture of the high and low melting point metals with a metal ofintermediate melting point in which the latter metal predominates, andthen pouring the resultant product into a bath of molten metalconsisting predominantly of the low melting point metal.

In testimony whereof, I aflix my signa- 30 ture.

THERON D. STAY.

